Process of recovering rubber from vulcanized-rubber waste.



m reclaim rubber gum from vulcanized rubber GRAY s'ramvron, or nwsxneon, MICHIGAN.

PROCESS OF RECOVERING- RUBBER FROM VULCANIZED-RUBBER WASTE.

No. Drawing.

'To'all whom it may concern Be it known that I, GRAY STAUNTON, a citizen of the United States, residing at Muskegon, in the county of Muskegon and state of Michigan, have invented certain new and useful Improvements in Processes of Recovering Rubber from Vulcanized- Rubber Waste, of which the following is a specification.

The object of my invention is to provide a new and useful process for the industrlal utilization of waste india rubber goods, such as .worn out vehicle tires, water hose, shoes, and the like, in which india rubber is present in sufficient quantities to render the process commercially efficient, this being effected by returning to the stock treated its original qualities so that it again can be employed as new material. The india rubber thus regenerated difli'ers in no way, substantially, from the natural india rubber as'regards its mastic, elastic and tenacious properties and can be again readily vulcanlzed 1ust as it'was initially vulcanized. The reclaimed product is so t and gummy so that it can be worked alone. Wlth011t 'tl18 necessity of adding fresh, new stock to the compound, if desired, and without the formatlon of lumps I and blisters while it is being milled.

It has long been the practice, in efforts to waste, or scrap, to submerge it in a solution and submit it to the action of steam, or other fluids, in closed vessels, or digesters, under pressure generally from 200 to 300 pounds per square inch, and for periods of tune ranging from 24 to 36 hours. The result is that the long continued h1gh temperat ure produces a change in the chemical constltutionof some of the fillers, in the rubber compound, and asoftening and weakening of the rubber itself. Furthermore, high pressure is dangerous and expensive and there is apractical limit beyond-whlch it is not safe to construct the digesters.

By the use of my invention the cost of reclaiming the rubber is greatly reduced and the character of the product recovered is of much greater value than by'the 01d processes.

In carrying my invention into effect I first grind up the rubber shoddy, or-waste to bereclaimed, into as fine con lomerate as practicable, in the ordinary rub er mill, reducing the waste to a highly comminuted or powdered mass. Notwithstanding that the Specification of Letters Patent.

Patented Jan. M, 1918.

Application filed June 20, 1912. Serial No. 704,734.

particles of the comminuted mass are small, they are of more or less globular form and present therefore a minimum of superficial area. For this reason intimate contact of the reagent with the material is limited to the surface exposed by the generally globular particles, and in order to more intimately scribed. After the stock, in a substantially dry state, has been ground or pulverized,

it is then. mixed with a pulverulent, substantially dry, chemical substance, or reagent, having a chemical affinity for the sulfur contained Within the stock to be reclaimed. There are a number of such known substances, such for instance as potassium carbonate, or sodium carbonate, or other alkal1ne reagents that may be employed for the purpose about to be described.

In. experiments which I have made, in using potassium carbonate, I have secured good results by incorporating 20 to 25 per cent. of potassium carbonate, in a dry powdered state, with the ground, comminuted rubber scrap, or shoddy, and thoroughly mixing the same. After the, mixing opera- ,tion has been completed I then place, preferably, the conglomerate mass in a mill, of usual type, such asthat in which the rubber scrap was ground, and pass the mixture through said mill, thereby mechanically forcing particles of the dry powdered reclaiming agent into each of thesmall particles of rubber waste, thus producing a thoroughly well distributed and intimate association mechanically effected ofevery particle of rubber waste with a suflicient quantity of the reagent, so that every particle of the rubber waste content is brought into intimate contact with particles of the reclaiming agent. The mill is so adjusted that each particle, or globule, of the resilient graunlar rubber waste as it passes through and between the rollers is dispanded, or

flattened out, and at this time the powdered,

or comminuted reclaiming agent,1s t reby forced into contact with the increase surfaces thus exposed so that when the particles \of rubber waste reassume their globular form, they intimately inclose more or less of the mixture impressed upon their enlarged surfaces. After the reclaiming agent has been thus thoroughly incorporated with the comminuted rubber waste, or stock, the conglomerate is then .placed in a suitable vessel,

or digester, in a substantially, dry state, and

is put into an oven and subjected to heat at a temperature above the melting pomt of sulfur, about 232 degrees Fah. and below the point at which the vulcanized rubber may be melted, or decomposed. -In practice ,I have found that to cook the mass at 300 produced by union of the sulfur and the reagent which are all soluble in Water. After the conglomerate has been washed, in the manner described, any residual alkali may be neutralized by adding the proper amount of acid, such as hydrochloric acid, in a suitably diluted solution, and then it may be further washed, if necessary.

While I have herein described in some particularity the process bg which my invention is carried into e ect it will, of course, be understood that I am not to be limited further than is defined by the appended claim.

Having described my invention, what I claim as new and desire to secure of Letters Patent of the United States is:

The process of reclaiming rubber, from vulcanized rubber waste, which consists in comminuting said waste, incorporating therewith, by mixing, a substantially dry, pulverulent reagent, having chemical aflinity for a vulcanizing agent contained in said waste, and while in a dry, loose, pulverulent state heating the mixture to a temperature not to exceed 300 degrees Fahrenheit, by application of dry heat thereto. i

In testimony whereof I hereunto set my hand in the presence of two witnesses.

GRAY. STAUNT N. I

In the presence of'- NORMAN T. THoMsoN, OSCAR C. OLSEN. 

